HK1010938A1 - Process for manufacturing a magnetic component made of an iron-based soft magnetic alloy having a nanocrystalline structure - Google Patents
Process for manufacturing a magnetic component made of an iron-based soft magnetic alloy having a nanocrystalline structure Download PDFInfo
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- HK1010938A1 HK1010938A1 HK98112053A HK98112053A HK1010938A1 HK 1010938 A1 HK1010938 A1 HK 1010938A1 HK 98112053 A HK98112053 A HK 98112053A HK 98112053 A HK98112053 A HK 98112053A HK 1010938 A1 HK1010938 A1 HK 1010938A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0206—Manufacturing of magnetic cores by mechanical means
- H01F41/0213—Manufacturing of magnetic circuits made from strip(s) or ribbon(s)
- H01F41/0226—Manufacturing of magnetic circuits made from strip(s) or ribbon(s) from amorphous ribbons
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
- H01F1/147—Alloys characterised by their composition
- H01F1/153—Amorphous metallic alloys, e.g. glassy metals
- H01F1/15333—Amorphous metallic alloys, e.g. glassy metals containing nanocrystallites, e.g. obtained by annealing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
- H01F1/147—Alloys characterised by their composition
- H01F1/153—Amorphous metallic alloys, e.g. glassy metals
- H01F1/15341—Preparation processes therefor
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/70—Nanostructure
- Y10S977/832—Nanostructure having specified property, e.g. lattice-constant, thermal expansion coefficient
- Y10S977/833—Thermal property of nanomaterial, e.g. thermally conducting/insulating or exhibiting peltier or seebeck effect
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- Engineering & Computer Science (AREA)
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- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Electromagnetism (AREA)
- Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Soft Magnetic Materials (AREA)
- Thin Magnetic Films (AREA)
- Powder Metallurgy (AREA)
- Hard Magnetic Materials (AREA)
- Manufacturing Of Steel Electrode Plates (AREA)
Abstract
The production of a magnetic component from a nanocrystalline iron based soft magnetic alloy of composition (in at. %) ≥ 60 % Fe, 0.1-3 % Cu, 0-25 % B, 0-30 (preferably ≤ 14) % Si, 0.1-30 % one or more of Nb, W, Ta, Zr, high-frequency, Ti and Mo and balance impurities, the sum of Si + B being 5-30 %, involves producing a toroidal preform by winding an amorphous strip of the alloy around a mandrel and carrying out one or more crystallisation anneal processes at 500-600 degrees C for 0.1-10 hrs. to form nanocrystals. The novelty comprises carrying out a relaxation heat treatment at below the crystallisation start temperature prior to crystallisation annealing.
Description
The present invention relates to a process for manufacturing a magnetic element from an iron-based soft magnetic alloy having a nanocrystalline structure.
Nanocrystalline magnetic materials are well known and have been described in particular in european patent applications EP0271657 and EP 0299498. These are iron-based alloys containing 60 atomic% or more of iron, copper, silicon, boron, and optionally at least one of niobium, tungsten, tantalum, zirconium, hafnium, titanium, and molybdenum, cast in the form of amorphous thin strips, and then subjected to heat treatment, thereby causing the occurrence of extremely fine crystals (crystal grain diameter less than 100 nm). These materials have magnetic properties which are particularly suitable for the manufacture of soft magnetic cores for electrical devices, such as residual current circuit breakers. In particular, they have excellent permeability and can have a wide hysteresis loop (Br/Bm ≧ 0.5) or a narrow hysteresis loop (Br/Bm ≦ 0.3), Br/Bm being the ratio of residual induction to maximum induction. A wider hysteresis loop is obtained when the heat treatment consists of a single annealing step at a temperature of 500-600 ℃. A narrower hysteresis loop is obtained when the heat treatment comprises an annealing step in at least one magnetic field, which annealing step may be used to cause the formation of nanocrystals.
However, nanocrystalline thin ribbons, or more precisely magnetic elements made from these thin ribbons, have the following disadvantages that limit their use. These disadvantages are that the magnetic properties are not stable enough above ambient temperature. This lack of stability leads to a lack of functional reliability of the residual current circuit breaker equipped with such a core.
The object of the present invention is to overcome the above-mentioned drawbacks and to provide a process for manufacturing a magnetic core from a nanocrystalline material having magnetic properties, with a significantly improved temperature stability.
For this purpose, the subject of the invention is a process for manufacturing a magnetic element from an iron-based soft magnetic alloy with nanocrystalline structure, whose chemical composition in atomic%: fe is more than or equal to 60 percent, Cu is more than or equal to 0.1 percent and less than or equal to 3 percent, B is more than or equal to 0 percent and less than or equal to 25 percent, Si is more than or equal to 0 percent and less than or equal to 30 percent, at least one element selected from niobium, tungsten, tantalum, zirconium, hafnium, titanium and molybdenum has the content of 0.1 percent to 30 percent, and the balance is impurities generated by smelting, the composition also satisfies the relation that Si + B is more than or equal to 5 percent and less than or equal to 30 percent, and the method comprises:
-manufacturing an amorphous thin strip from a magnetic alloy,
-manufacturing a blank for a magnetic element from a thin strip,
-subjecting the magnetic element to a crystallization heat treatment comprising at least one annealing step at a temperature comprised between 500 ℃ and 600 ℃ for a time comprised between 0.1 and 10 hours, in order to form nanocrystals; before the crystallization heat treatment, a relaxation heat treatment is performed at a temperature lower than a recrystallization start temperature of the amorphous alloy.
The relaxation heat treatment can be heat preservation for 0.1 to 10 hours at the temperature of 250 to 480 ℃.
The relaxation heat treatment may also be a slow heating from ambient temperature to a temperature above 450 ℃ with a heating rate between 250 ℃ and 450 ℃ of 30 ℃/hour to 300 ℃/hour.
Depending on the desired magnetic properties, in particular on the desired shape of the hysteresis loop, at least one annealing step constituting the heat treatment can be carried out in a magnetic field according to the prior art.
The process is particularly suitable for being applied to the iron-based soft magnetic alloy with the nanocrystalline structure, wherein Si in the chemical composition of the iron-based soft magnetic alloy is less than or equal to 14%.
The invention is described in more detail below, but is not limited thereto and is shown by way of example.
In order to produce magnetic components in large volumes, such as cores for AC-type residual current circuit breakers (sensitive to alternating fault currents), amorphous-structured soft magnetic alloy ribbons are used which are capable of obtaining a nanocrystalline structure, the alloy consisting essentially of iron in a proportion of more than 60 atomic%, and also comprising:
-0.1 to 3 at.% copper, preferably 0.5 to 1.5 at.%;
0.1 to 30 at.% of at least one element selected from the group consisting of niobium, tungsten, tantalum, zirconium, hafnium, titanium and molybdenum, preferably 2 to 5 at.%, and most preferably 2 to 4 at.%;
silicon and boron, the total content of these elements being between 5 and 30 at.%, preferably between 15 and 25 at.%, the boron content being up to 25 at.%, preferably between 5 and 14 at.%; the silicon content may be as high as 30 atomic%, preferably 12 to 17 atomic%.
In addition to these elements, the alloy may contain low concentrations of impurities brought about by the raw materials or produced by smelting.
In a known manner, amorphous ribbons are obtained by very rapid solidification of the liquid alloy, for example by casting on a cooling wheel.
The core blank is also manufactured in a known manner by winding a thin strip around a mandrel, cutting it and fixing its tail end by spot welding, so as to obtain a circular core having a rectangular cross section.
In order to obtain the final magnetic properties of the blank, an annealing step called "relaxation annealing" is first carried out at a temperature lower than the temperature at which the amorphous ribbon starts to crystallize, preferably at a temperature of 250 ℃ to 480 ℃, and then a crystallization annealing step is carried out, optionally in a magnetic field, and optionally followed by an annealing step in a low temperature magnetic field. In fact, the inventors have found that, quite unexpectedly, such relaxation annealing has the advantage of causing a very significant reduction in the sensitivity of the magnetic properties of the core to temperature. The inventors have also found that relaxation annealing prior to recrystallization annealing has the additional advantage of reducing the dispersion of magnetic properties of mass-produced magnetic cores.
The crystallization annealing is used for precipitating the nanocrystalline with the size less than 100 nanometers, preferably 10-20 nanometers in the amorphous matrix. Such extremely fine crystals can achieve desired magnetic properties. The crystallization annealing consists of holding at a temperature above the temperature at which crystallization starts to occur, but below the temperature at which secondary phases with reduced magnetic properties appear. Typically, the crystallization annealing temperature is between 500 ℃ and 600 ℃, but this temperature can be optimized, for example, by experimentally determining the temperature at which the maximum permeability is reached for each thin strip. The crystallization annealing temperature may then be chosen to be equal to this temperature, or better to be about 30 ℃ higher.
In order to improve the shape of the hysteresis loop, which is necessary for class a residual current circuit breakers (sensitive to bias fault currents), a crystallization anneal may be performed in a transverse magnetic field. The crystallization may also be accomplished by an annealing step performed in a transverse magnetic field at a temperature below the temperature at which crystallization begins to occur, for example, about 400 ℃.
More generally, the heat treatment of the magnetic element blank includes a relaxation annealing step, optionally a crystallization annealing step in a magnetic field, and optionally a supplemental annealing step in a magnetic field.
The relaxation annealing is carried out equally effectively on the amorphous ribbon itself or on the magnetic element blank before the crystallization annealing, the relaxation annealing consisting of a soaking at a constant temperature, preferably for a time comprised between 0.1 and 10 hours. This annealing can also consist of a slow ramp-up and must be carried out, for example, before the crystallization annealing, at a ramp-up rate of between 30 ℃/hour and 300 ℃/hour, at least between 250 ℃ and 450 ℃; the temperature rise rate is preferably about 100 ℃ per hour.
In all cases, the heat treatment is preferably carried out in a furnace with a controlled neutral or reducing atmosphere.
As an example, alloy Fe was produced by direct cooling on a cooling wheel73Si15B8Cu1Nb3Two thin strips of (73 at% iron, 15 at% silicon, etc.) 20 μm thick and 10mm wide. Two batches of blanks for magnetic cores, respectively referenced a1 and a2 (for the first thin strip) and B1 and B2 (for the second thin strip), were made from each thin strip. The blanks of the respective batches for magnetic cores a1 and B1 were heat treated in accordance with the present invention and were configured to undergo a relaxation annealing step at 400 c for 3 hours, followed by a crystallization annealing step at 530 c for 3 hours. Each of the blanks for cores A2 and B2 was used as a comparative example, and a single crystallization annealing step was performed at 530 ℃ for 3 hours according to the prior art. The 50Hz maximum permeability was measured on four batches of blanks for magnetic cores at different temperatures between-25 c and 100 c and expressed as a percentage of the 50Hz maximum permeability at 20 c. The results are as follows:
| sample (I) | -25℃ | -5℃ | 20℃ | 80℃ | 100℃ |
| A1 (the invention) | 100％ | 102％ | 100％ | 93％ | 86％ |
| A2 (comparison example) | 102％ | 103％ | 100％ | 87％ | 78％ |
| B1 (inventive) | 97％ | 98％ | 100％ | 88％ | 78％ |
| B2 (comparison example) | 98％ | 99％ | 100％ | 75％ | 60％ |
The interpretation of these results must be examined separately for the case of samples A1 and A2 on the one hand and for the case of samples B1 and B2 on the other hand. This is because although all samples were composed of the same alloy, the two thin strips used were manufactured separately and thus slightly different in properties.
That is, it can be seen that, for both of the groups a1, a2 and the groups B1, B2, the decrease in permeability due to heating to 80 ℃ or 100 ℃ is much smaller in the samples according to the present invention than in the comparative example. For example, the loss of permeability at 100 c, is about half that of the samples made by the prior art.
In addition to the effect obtained with respect to the temperature stability of magnetic properties, the present inventors have found that the present invention improves the reproducibility of magnetic properties of mass-produced magnetic cores. This advantageous effect is illustrated below by two examples.
A first example relates to a circular core made of a thin strip 20 μm thick and 10mm wide, consisting of (in atomic%) Fe73.5Si13.5B9Cu1Nb3The alloy of (2) is obtained by direct quenching on a cooling wheel. After on-wheel quenching, the thin strip was indeed completely amorphous as verified by X-ray. The strip is then divided into three sections, one section A remaining in the quenched state, and the other two sections B and C being subjected to a relaxation annealing, one B being at 400 ℃ for 1 hour and the other B being at 450 ℃ for 1 hour. The coercive field was measured and its minimum and maximum values were mOe (1mOe ═ 0.079577 a/m): a, 80-200 mOe, B and C, 25-35 mOe. These results indicate that the effect of the relaxation annealing not only reduces the dispersion of the coercive field, but also reduces its value very significantly.
Then, blanks for circular cores were formed using three thin strip portions, and in order to obtain a wider hysteresis loop, these cores were first subjected to crystallization annealing at 530 ℃ for 1 hour and then subjected to annealing in a transverse magnetic field at 400 ℃ so as to obtain a narrower hysteresis loop. Values of coercive force field, 50Hz maximum permeability, and Br/Bm ratio (ratio of residual magnetic induction to saturation magnetic induction) for only a narrow hysteresis loop were determined.
The results are as follows:
a) wider hysteresis loop
| Sample (I) | Relaxation treatment | Coercive force field (mOe) | 50Hz maximum magnetic permeability |
| A | Is free of | 6.1 | 650,000 |
| B | At 400 ℃ for 1 hour | 5.2 | 690,000 |
| C | 1 hour at 450 DEG C | 5.1 | 760,000 |
b) Narrower hysteresis loop
| Sample (I) | Relaxation treatment | Coercive force field (mOe) | Br/Bm | 50Hz maximum magnetic permeability |
| A | Is free of | 5 | 0.12 | 200,000 |
| B | At 400 ℃ for 1 hour | 3.8 | 0.08 | 215,000 |
| C | 1 hour at 450 DEG C | 3.4 | 0.07 | 205,000 |
These results clearly show the improvement in magnetic properties resulting from the relaxation treatment: the coercive force field is reduced, the maximum magnetic conductivity is improved, and a narrower magnetic hysteresis loop is easy to obtain.
A second example relates to a circular core made of a thin strip 20 μm thick and 10mm wide, consisting of (in atomic%) Fe73Si15B8Cu1Nb3The alloy of (2) is obtained by direct quenching on a cooling wheel.
Two batches of 300-lap round cores were made with an automatic winder, with an inside diameter of 11mm and an outside diameter of 15 mm. The two batches were then processed in a furnace under a neutral atmosphere. Reference batch a was subjected to a crystallization annealing step only for 1 hour at 530 ℃. The second batch was processed according to the invention: a relaxation annealing step was first performed at 400 c for 1 hour, followed by a crystallization annealing step at 530 c. The circular core was placed in the housing and wedged with a foam washer. The mean and standard deviation of the 50Hz maximum permeability were determined for each batch.
The results are as follows:
| treatment of | 50Hz maximum permeability average | Standard deviation of 50Hz maximum magnetic permeability |
| No relaxation treatment (batch A) | 585,000 | 28,000 |
| With relaxation treatment (batch B) | 615,000 | 20,000 |
This shows that the effect of the relaxation annealing improves the mean value of the maximum permeability on the one hand and reduces the dispersion on the other hand.
Then, two batches were processed in a transverse magnetic field at 400 ℃ in order to obtain a narrower hysteresis loop. The coercive field, Br/Bm ratio and 50Hz permeability at 5mOe were measured. The results are as follows:
| treatment of | Coercive force field (mOe) | Br/Bm | Permeability of 50Hz at 5mOe |
| No relaxation treatment (batch A) | 5.2 | 0.08 | 117,000 |
| With relaxation treatment (batch B) | 4.3 | 0.06 | 124,000 |
These results clearly show the improvement in magnetic properties brought about by the relaxation treatment: the reduction of coercive force field, the increase of 50Hz magnetic permeability under 5mOe and the extremely easy obtaining of narrower hysteresis loop.
Claims (4)
1. A process for manufacturing a magnetic component from an iron-based soft magnetic alloy having a nanocrystalline structure, the iron-based soft magnetic alloy having a chemical composition in atomic percent of: fe is more than or equal to 60 percent, Cu is more than or equal to 0.1 percent and less than or equal to 3 percent, B is more than or equal to 0 percent and less than or equal to 25 percent, Si is more than or equal to 0 percent and less than or equal to 30 percent, at least one element selected from niobium, tungsten, tantalum, zirconium, hafnium, titanium and molybdenum has the content of 0.1 percent to 30 percent, and the balance is impurities generated by smelting, the composition also satisfies the relation that Si + B is more than or equal to 5 percent and less than or equal to 30 percent, and the method comprises the:
-manufacturing an amorphous thin strip from a magnetic alloy;
-forming a circular core from a thin strip of magnetic material by winding the thin strip around a mandrel, a blank for a magnetic element being made from the thin strip;
-subjecting the magnetic element blank to a crystallization heat treatment comprising at least one annealing step at a temperature of between 500 ℃ and 600 ℃ for a holding time of between 0.1 and 10 hours, in order to form nanocrystals; the method is characterized in that before crystallization heat treatment, the temperature is kept at 250-480 ℃ for 0.1-10 hours for relaxation heat treatment.
2. Process according to claim 1, characterized in that the crystallization annealing is carried out in a magnetic field.
3. Process according to claim 1 or 2, characterized in that the post-annealing step is carried out in a magnetic field at a temperature below the crystallization onset temperature.
4. A process according to claim 1 or 2, characterized in that the chemical composition of the alloy is Si ≦ 14%.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9615197 | 1996-12-11 | ||
| FR9615197A FR2756966B1 (en) | 1996-12-11 | 1996-12-11 | METHOD FOR MANUFACTURING A MAGNETIC COMPONENT MADE OF SOFT MAGNETIC ALLOY IRON BASED HAVING A NANOCRYSTALLINE STRUCTURE |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| HK1010938A1 true HK1010938A1 (en) | 1999-07-02 |
| HK1010938B HK1010938B (en) | 2004-06-04 |
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Also Published As
| Publication number | Publication date |
|---|---|
| KR19980064039A (en) | 1998-10-07 |
| JPH10195528A (en) | 1998-07-28 |
| HUP9702383A2 (en) | 1998-07-28 |
| CN1134034C (en) | 2004-01-07 |
| TR199701599A3 (en) | 2000-07-21 |
| FR2756966A1 (en) | 1998-06-12 |
| PL323663A1 (en) | 1998-06-22 |
| TR199701599A2 (en) | 2000-07-21 |
| CZ293837B6 (en) | 2004-08-18 |
| CZ398397A3 (en) | 1998-07-15 |
| DE69715575D1 (en) | 2002-10-24 |
| CN1185012A (en) | 1998-06-17 |
| EP0848397B1 (en) | 2002-09-18 |
| EP0848397A1 (en) | 1998-06-17 |
| HU216168B (en) | 1999-04-28 |
| SK161897A3 (en) | 1998-12-02 |
| HUP9702383A3 (en) | 1998-08-28 |
| TW561193B (en) | 2003-11-11 |
| ES2184047T3 (en) | 2003-04-01 |
| ZA9710780B (en) | 1998-06-12 |
| FR2756966B1 (en) | 1998-12-31 |
| DE69715575T2 (en) | 2003-05-22 |
| AU4519997A (en) | 1998-06-18 |
| SK284008B6 (en) | 2004-07-07 |
| AU731520B2 (en) | 2001-03-29 |
| ATE224582T1 (en) | 2002-10-15 |
| PL184208B1 (en) | 2002-09-30 |
| US5911840A (en) | 1999-06-15 |
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| PF | Patent in force | ||
| PC | Patent ceased (i.e. patent has lapsed due to the failure to pay the renewal fee) |
Effective date: 20071210 |